光學微環(huán)生物傳感器的設計與優(yōu)化


摘  要
　　　微環(huán)諧振腔具有高品質(zhì)因數(shù)、低成本的特點。由于它基于平面波導結(jié)構(gòu)，因而易于同其它光電芯片和微流控芯片集成，并且進行化學表面處理。另外，諧振效應的引入能夠在提高靈敏度的同時大大縮小器件的尺寸，所以基于微環(huán)諧振腔的生物傳感器是一種高靈敏度的，可對微量生物物質(zhì)進行探測的傳感器。本文在國家自然科學基金的資助下，對微環(huán)生物傳感器的理論模型和性能參數(shù)做了系統(tǒng)性的分析研究，完成的主要工作有以下幾點：
　　　(1) 基于模式耦合理論和時域有限差分法，深入研究直波導與彎曲波導的耦合性質(zhì)，并在此基礎上建立微環(huán)諧振腔的理論模型，得到器件的主要參數(shù)如自由頻譜區(qū)間FSR和品質(zhì)因數(shù)Q的表達式；
　　　(2) 根據(jù)微環(huán)傳感器的工作原理，將總靈敏度分為波導靈敏度和器件靈敏度，著重分析器件靈敏度與傳輸因子σ、自耦合因子t、以及工作波長λ的關(guān)系，并結(jié)合上述參數(shù)與其他結(jié)構(gòu)參數(shù)的關(guān)系，提出具體的設計和優(yōu)化方案；
　　　(3) 利用高斯函數(shù)對原洛倫茲響應譜的近似，得到器件品質(zhì)因數(shù)Q與器件靈敏度的關(guān)系，從而推出基于品質(zhì)因數(shù)和系統(tǒng)信噪比(SNR)求得探測極限的理論方法，該法對以監(jiān)測強度變化為工作原理的微環(huán)傳感器普遍適用；
　　　(4) 推出在具有相位噪聲的非理想光源激勵下的器件響應總譜，進而得出具有不同線寬的激光光源對微環(huán)性能影響的關(guān)系式。
　　　
　　　關(guān)鍵詞：生物傳感器   微環(huán)諧振腔   靈敏度分析   探測極限 
Abstract
　　　Due to the compatibility with standard CMOS platform, planar microring resonator with high quality factor can be fabricated at low cost. Based on planar waveguides, it not only allows surface chemical modifications, but can also be integrated with other optoelectronic devices and microfluidic handling, leading to highly integrated and intelligent sensing chips. Furthermore, it offers a unique advantage of reducing the device size without sacrificing the sensitivity by virtue of the resonance. Therefore, micoring resonator biosensor is highly sensitive that can detect minute amount of analytes. Supported by the National Science Foundation of China, the theoretical model and sensitivity are systematically studied in this thesis. The main contents are listed as follows:
　　　(1) The coupling property of the bent-straight coupler is thoroughly investigated, based on coupled mode theory and FDTD method. Theoretical method is established, from which expressions of key parameters such as FSR and Q factor are derived.
　　　(2) The overall sensitivity of the device is divided into two contributions: waveguide sensitivity and device sensitivity. The relations of device sensitivity and transmission coefficient σ, self coupling coefficient t, and operating wavelength λ are studied, based on which a design and optimization guideline is summarized.
　　　(3) By approximating the original Lorentzian lineshape with a Gaussian function, an explicit relation between the quality factor and the device sensitivity is studied. The detection limit is thereafter derived through the quality factor and signal-to-noise ratio (SNR), which is in good agreement with experimental results and universal for microring resonator sensors based on intensity variation.
　　　(4) The overall response is derived, with the phase noise of laser source taken into account. The influence of laser linewidth on the overall performance is studied.
　　　
　　　Keywords: biosensor    microring resonator   sensitivity analysis
　　　　　　　　detection limit
目  錄
摘  要 I
Abstract II
1  緒論
1.1  引言 (1)
1.2  微環(huán)諧振腔發(fā)展簡述 (2)
1.3  微環(huán)諧振腔的應用 (3)
1.4  微環(huán)諧振腔的分類 (3)
1.5  本文的工作 (5)
2  光學微環(huán)理論基礎
2.1  引言 (7)
2.2  直-彎波導耦合器 (7)
2.3  單直波導耦合微環(huán)模型 (18)
2.4  雙直波導耦合微環(huán)模型 (21)
3  微環(huán)傳感器靈敏度分析及優(yōu)化設計
3.1  引言 (25)
3.2  微環(huán)傳感器的工作原理 (25)
3.3  傳感性能的衡量指標 (26)
3.4  靈敏度分析 (27)
3.5  微環(huán)傳感器的優(yōu)化設計 (35)
4  微環(huán)傳感器的探測極限
4.1  引言 (38)
4.2  探測極限 (39)
5  激光器隨機相位噪聲的影響
5.1  引言 (46)
5.2  具有相位噪聲的非理想激光器輸出譜 (46)
5.3  非理想激光器對微環(huán)的影響 (47)
6  總結(jié)與展望 (51)
致  謝 (52)
參考文獻 (53)